Combined thermal insulation bolt connection structure

Abstract

The invention provides a combined thermal insulation bolt connection structure. The combined thermal insulation bolt connection structure comprises a piston steel crown, a metal thermal insulation pad, elastic combined gaskets, bolts and an aluminum body; the metal thermal insulation pad is arranged between the piston steel crown and the contact surface of the aluminum body, the piston steel crown is provided with bolt holes for bolt fastening, the metal thermal insulation pad and the aluminum body are provided with through holes used for allowing the bolts to penetrate through, the piston steel crown, the metal thermal insulation pad and the aluminum body are fastened together through multiple bolts, and the elastic combined gaskets are arranged between the heads of the bolts and the aluminum body. The combined thermal insulation bolt connection structure has the following advantages that the metal thermal insulation pad is arranged between the piston steel crown and the aluminum body, therefore, heat is partially isolated through the thermal insulation pad, and the temperature of the aluminum body is controlled within the reasonable range; the elastic combined gaskets are adopted between the bolts and the contact surface of the aluminum body, therefore, part of deformation can be compensated when the piston is heated to be expanded or cooled, and the tensile loads of the bolts are reduced; the contact stress of the aluminum body bearing surface can be reduced, and then aluminum body cracking is prevented.

Description

technical field [0001] The invention belongs to the technical field of engine pistons, and in particular relates to a bolt connection structure of a combined heat-insulating piston. Background technique [0002] At present, four-stroke diesel engines mostly use cast aluminum pistons to reduce the mass of the pistons and reduce the reciprocating inertial force of the pistons. However, the limit temperature that the cast aluminum pistons can withstand is low, about 420 degrees. As the combustion pressure of the engine continues to increase , the temperature of the piston continues to rise, and the cast aluminum piston can no longer withstand such a high temperature, which can easily lead to piston ablation. [0003] In order to solve the above problems, one method is to install a thermal insulation coating on the top surface of the piston to reduce the heat transfer from the combustion chamber to the piston and reduce the surface temperature of the piston. Cracking, falling o...

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Problems solved by technology

[0002] At present, four-stroke diesel engines mostly use cast aluminum pistons to reduce the mass of the pistons and reduce the reciprocating inertial force of the pistons. However, the limit temperature that the cast aluminum pistons can withstand is low, about 420 degrees. As the combustion pressure of the engine continues to increase , the temperature of the piston continues to rise, and the cast aluminum piston can no longer withstand such a high temperature, which can easily lead to piston ablation

[0003] In order to solve the above problems, one method is to install a thermal insulation coating on the top surface of the piston to reduce the heat transfer from the combustion chamber to the piston and reduce the surface temperature of the piston. Cracking, falling off and other problems, the reliability problem is still difficult to solve, so it is not recommended; another method is to use the combined piston with steel top and aluminum skirt. The steel top can withstand high temperature and is not easy to cause piston ablation, but the steel The temperature transmitted from the top to the aluminum body is relatively high, and the cooling oil channel must be used for cooling, which increases the difficulty of design and processing

In addition, the piston with such a combined structure needs to be connected by bolts. When the piston is heated and expanded, the tensile load on the piston increases sharply, resulting in a very large contact pressure between the bolt and the aluminum body, and it is easy to cause the aluminum body to be in contact with the bolt head. location cracking

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